StableBit DrivePool - State of the art, file based drive pooling software.
OpenMediaVault - OpenMediaVault is the next generation network attached storage (NAS) solution based on Debian Linux.
unRAID Server - A scalable, consumer-oriented, server operating system.
FreeNAS - FreeNAS is a storage operating system strong and robust enough to meet the needs of enterprise level businesses.
SnapRAID - A backup program for disk arrays. It stores parity information of your data and it recovers from up to six disk failures.
Rockstor - Rockstor is a free and open source NAS (Network Attached Storage) operating system.